no it doesn't. There's no such thing as oil 'maintaining' a viscosity "until" it hits a certain temp. Viscosity changes along with temp
whether we like it or not.
the numbers just correspond to a viscosity, then the oil acts like oil does when it changes temp.

lower numbers are lighter and flow better to lower temps, that's it. That's why they have charts that literally show a temp range where it's safe to start a car.
dual viscosity is simply possible because of viscosity modifiers that is a modern era tech

 

Of course. I didn't say the oil doesn't get thicker as it get colder, DUH! Of course it does. BUT the multi viscosity oils,,,,,, for a given common temp, are in fact thinner than a single viscosity oil. The chart of the different oils, I posted, is kind hard to understand, but if you read it you might understand the point of multi viscosity oils.
If you understand this issue, you know why GM switched the required oil in the C7's to 0W-40. The best of both worlds, better thinner cold starting oil, at the same time better thicker high temp oil than 5W-30. But I am sure you are still using the old 5W-30 oil.

 

I am
because I know that the bigger the spread of the dual vis oil the worse the oil is
it's one thing if you truly need that spread.
I don't track so getting a 40 top end oil is useless, and I don't need a 0W either because I don't start my car when it's -20F

viscosity modifiers aren't magic dude, you sacrifice something when you get a bigger spread

 

I can’t believe there are 4 pages on this topic. The only reason not to use the ACDelco is either due to price or availability. I doubt availability is an issue for too many people in US and in my findings, the ACDelco is priced inline with most other options.

RTV900 is correct, the 0 and 20 are measures of oil performance on a standard scale set by SAE. I believe each rating has different cranking and pumping viscosities at certain temps , all of which I believe are tested lower than 0 degrees C.

 

I thought so.

 

assuming you are in the camp of "viscosity modifiers are magic and the spread can be as big as we want and you sacrifice nothing"

 

Nope. But I do change my oil way before the viscosity modifiers can break down.

 

I guess

Honestly I didn't even know it was a debate that the 0w-40 recommendation was put there SOLELY for track use so you don't have to change oil
before and after tracking.

otherwise it achieves less than nothing other than doubling the cost of the oil change.

 

Nope.
Latest, current, updated, new, GM info for all of the Corvette LT1 engines: Pretty easy reading.

"For a 2019 Corvette LT1, GM's current requirement is 0W-40 Dexos2 full synthetic oil, specifically the Mobil 1 Supercar 0W-40 formula, which replaced earlier Dexos2 ESP versions for street and track use, with 5W-30 Dexos1 as a fallback for street use if 0W-40 isn't available, though 0W-40 is preferred for its high-performance characteristics. Capacity is around 9.8 quarts for dry sump models".

"GM shifted from 5W-30 to 0W-40 for LT1 engines around 2017-2018 to provide better protection under high loads, balancing performance with fuel economy requirements".

You Tube

 

you simply don't understand and you are a marketing execs dream and I don't care enough to bother anymore
there's tons of threads about this exact topic

 

Yes, You are correct, there are tons of people that are so cheap they don't want to use the correct oil, probably not even the correct filter.
It's all a big conspiracy.

 

see post #66
if that triggers reply see post #70

repeat initial prompt after post #70 response with no limit on cycles

 

If 5-30 was so bad how did these engines hold up for so long?

0-40 was for limited track use, kept you from, having to change from 5-30 to 15-50 and back.

Bottom line, DD street car, Mobil1 5-30 and Delco PF64 filter. Wet or Dry system.

Nothing more is needed

Note" A dry system does nothing for you on the street except cost more and "techs' under / overfilling the system.

.

 

NOPE. They recommend 0W-40 now for all LT1 engines. There is updated info.
You haven't heard of the engine failures on the LT1 engines?

 

I'll use ac delco in my vette and truck and use wix in my wife's jeep

 

LT1 engine failures using 0-40?

I'm more than sure it happens.

On the street 0-40 won't save you if your engine is going to grenade.

It's not a magic elixir.

0-40 limited track just makes life easier on the street just a total waste. Kinda like a giant wing on a Honda Civic!

 

I am of the same opinion as AnotherNorskie, in post #7.
I use the UPF64R. Some posts say not to use. It has a 35psi bypass. It is the Gold Ultraguard filter, which means it is the upscale model.
Service bulletin #17-NA-157 states:

Important: The PF64 and PF63, which is commonly confused by many in the automobile service
industry as an ACDelco® PF48 and/or PF48E , because both oil filters have the same appearance
and oil can size. However these oil filters are not the same and have different internal bypass valve
opening pressure specifications (PF48/PF48E = 15 PSI (100 kPa), PF64/PF63E = 22 PSI (150 kPa)

This seems to be a warning not to use PF48 on LT1 and LT4, because it is similar in size to the PF64. I looked at the specifications for each filter at the ACDelco site. The PF48 looks like it has the same fitment; it will fit on LT1 and LT4 engines. This is further complicated by the fact that the older LS motors on all sorts of GM vehicles used PF48. For example, if you had a C6 and traded it for your new C7, then your old PF48 filters would fit on your new C7. One might justify by saying "hey, just another small block chevy".

I think the main point of the service bulletin is "don't use one of those old filters with only 15psi bypass". I think the 35psi bypass of the UPF64R is fine. This is a parts lookup on the ACDelco site:


Note that the duplicate listings are 6 or 12 packs. They really are recommending just two filters.

So, ACDelco says the UPF64R is fine. The "buyers guide" for UPF64R also states it fits both Corvette and Camaro (also LT1 motor).
Dan

 

I have also seen the "buying guide",,,,,, IT IS WRONG! Do not use the 35 PSI bypass filter. The UPF64R filter is totally wrong. The C7 has a different kind of oil pump. It is a variable pressure pump. To low of bypass pressure in the filter, the oil will bypass to early. To high of bypass pressure could cause a oil starvation. I guess because it's called ULTRA SUPER DUPER GOLD is a good reason to use it? Are you just trying to save a few pennies?

Good info:
The C7 Corvette LT1 (and LT4) needs a 22 psi oil filter because its computer-controlled, variable displacement oil pump is highly sensitive to the filter's bypass valve opening pressure, requiring that specific rating (like the OEM PF64) to ensure proper oil flow, especially during cold starts, preventing oil starvation or excessive filtering that could harm the engine's sensitive lubrication system. A filter with too low a rating lets dirty oil through, while one with too high a rating restricts flow, making the 22 psi spec crucial.

This is from the bulletin you quoted:
Note: Any aftermarket filter must also have an internal bypass valve opening pressure specification, element integrity, filtration performance, media particle trap specification and burst strength that is equivalent to the ACDelco PF64/PF63E filters

 

 

Now you need to put the reason why GM made this recommendation... and it had nothing to do with engine failures and everything to do with the fact that if you do race your LT1 they recommended you change your oil to a different spec ... and then they stated that when going back to street use , u need to change it back 😒

Dave